Resonance Raman spectroscopy is a novel technique of laser light scattering by excitation of vibrational modes of a chromophore within its electronic absorption band. This "resonance" phenomenon produces large enhancements in intensity even at natural concentration levels of biological molecules. We have applied this technique to (1) a study of cytochrome c and various heme-protein analogs and (2) to the respiratory protein, hemocyanin. In the former study, the dependence of the resonance Raman spectrum of the heme vibrations upon the oxidation and spin state of the iron atom were characterized. In the case of hemocyanin, we have the first direct evidence for the electronic structure of the oxygen: copper complex in oxyhemocyanin; oxygen is bound as a peroxide ion to a pair of cupric ions. We propose to begin a systematic analysis of the electronic and molecular structures of the multi-copper proteins, ceruloplasmin, laccase and ascorbate oxidase, all of which are characterized (by optical and electron spin resonance spectra) to contain three different types of copper atoms per molecule. These proteins also exhibit oxidase activity. By analogy to our hemocyanin studies, we intend to elucidate the oxygen binding by these proteins and determine the oxidation states of bound oxygen and the various types of copper atoms. Furthermore, we wish to obtain a more detailed understanding of the atomic structure of the copper sites for both the copper-dimer systems (hemocyanin and tyrosinase and the multi-copper systems (laccase, ceruloplasmin and ascorbate oxidase).